In modern four wheeled vehicles, such as cars, electrical motors may provide an alternative to the traditional combustion engines, as well as providing additional control of drive torque distribution by so called torque vectoring.
In case where the electrical motor is providing driving torque, such electrical propulsion motors may be arranged as the only driving unit of the vehicle, or in series or in parallel with a combustion engine thus forming a so called hybrid vehicle.
One example of a driving configuration including an electrical driving motor, as well as a torque vectoring motor, is described in WO02010101506 by the same applicant.
The electrical power system of today's passenger cars is normally based on 12V. Due to the relatively low voltage proposed solutions for high electrical power utilities, such as electrically powered propulsion units, require additional power supplies and high power electronics.
During recent years there is a trend of replacing the 12V system with an electrical power system being based on 48V. As the electrical power increases new and improved solutions may be applicable, replacing the previous solutions requiring additional high power electronics.
The above-mentioned prior art driving configuration includes a high power electrical motor for propulsion purposes, and a smaller electrical motor for torque vectoring purposes. Should 48V be available, it would be possible to develop a design for hybrid drive using only a single electrical motor, as well as a transmission being configured to be shifted between a first mode in which the electrical motor is used as a secondary drive source for propulsion, and a second mode in which the electrical motor is used for redistributing driving torque (i.e. from the primary drive).
An electrical motor, either used for propulsion, torque vectoring, or both, may be equipped with hydraulically actuated gears in order to provide a wider range of operating parameters of the electrical motor, e.g. with respect to torque output and rotational speed.
In addition to this, there is also a need for cooling the electrical machine. This may be done by supplying oil to the electrical machine, in which the cooling oil is circulated around the rotating parts of the electrical machine.
The use of a shifting mechanism for actuating a gear switch, as well as an electrical motor for propulsion, torque vectoring, or both requires two hydraulic systems. In order to reduce complexity and costs it would therefore be advantageous with a single hydraulic system capable of providing gear switch as well as cooling.